前言

网上开源的是构建同等数量的 EditText，这种存在很多缺陷，主要如下

1、数字 / 字符键盘切换后键盘状态无法保存

2、焦点切换无法判断

3、光标位置无法修正

4、切换过程需要做很多同步工作

解决方法

为了解决上述问题，使用 TextView 实现输入框，需要解决的问题是

1、允许 TextView 可编辑输入，这点可以参考EditText的实现

2、重写 onDraw 实现，不实用原有的绘制逻辑。

3、重写光标逻辑，默认的光标逻辑和Editor有很多关联逻辑，而Editor是@hide标注的，因此必须要重写

4、重写长按菜单逻辑，防止弹出剪切、复制等弹窗。

代码实现

首先我们要继承TextView或者AppCompatTextView，然后实现下面的操作

变量定义

//边框颜色
private int boxColor = Color.BLACK;

//光标是否可见
private boolean isCursorVisible = true;
//光标
private Drawable textCursorDrawable;
//光标宽度
private float cursorWidth = dp2px(2);
//光标高度
private float cursorHeight = dp2px(36);
//是否展示光标
private boolean isShowCursor;
//字符数量控制
private int inputBoxNum = 5;
//间距
private int mBoxSpace = 10;

关键设置

super.setFocusable(true); //支持聚焦
super.setFocusableInTouchMode(true); //支持触屏模式聚焦
//可点击，因为聚焦的view必须是可以点击的，这里你也可以设置个clickListener，效果一样
super.setClickable(true);
super.setGravity(Gravity.CENTER_VERTICAL);
super.setMaxLines(1);
super.setSingleLine();
super.setFilters(inputFilters);
super.setLongClickable(false);// 禁止复制、剪切
super.setTextIsSelectable(false); // 禁止选中

绘制逻辑

TextPaint paint = getPaint();

float strokeWidth = paint.getStrokeWidth();
if(strokeWidth == 0){
//默认Text是没有strokeWidth的，为了防止绘制边缘存在问题，这里强制设置 1dp

    paint.setStrokeWidth(dp2px(1));

    strokeWidth = paint.getStrokeWidth();

}

paint.setTextSize(getTextSize());

float boxWidth = (getWidth() - strokeWidth * 2f - (inputBoxNum - 1) * mBoxSpace) / inputBoxNum;
float boxHeight = getHeight() - strokeWidth * 2f;
int saveCount = canvas.save();


Paint.Style style = paint.getStyle();

Paint.Align align = paint.getTextAlign();

paint.setTextAlign(Paint.Align.CENTER);

String text = getText().toString();
int length = text.length();

int color = paint.getColor();

for (int i = 0; i < inputBoxNum; i++) {


    inputRect.set(i * (boxWidth + mBoxSpace) + strokeWidth,

            strokeWidth,

            strokeWidth + i * (boxWidth + mBoxSpace) + boxWidth,

            strokeWidth + boxHeight);


    paint.setStyle(Paint.Style.STROKE);

    paint.setColor(boxColor);
//绘制边框

    canvas.drawRoundRect(inputRect, boxRadius, boxRadius, paint);

//设置当前TextColor
int currentTextColor = getCurrentTextColor();

    paint.setColor(currentTextColor);

    paint.setStyle(Paint.Style.FILL);
if (text.length() > i) {
// 绘制文字，这里我们不过滤空格，当然你可以在InputFilter中处理
String CH = String.valueOf(text.charAt(i));
int baseLineY = (int) (inputRect.centerY() + getTextPaintBaseline(paint));//基线中间点的y轴计算公式

        canvas.drawText(CH, inputRect.centerX(), baseLineY, paint);

    }

//绘制光标
if(i == length && isCursorVisible && length < inputBoxNum){
Drawable textCursorDrawable = getTextCursorDrawable();
if(textCursorDrawable != null) {
if (!isShowCursor) {

                textCursorDrawable.setBounds((int) (inputRect.centerX() - cursorWidth / 2f), (int) ((inputRect.height() - cursorHeight) / 2f), (int) (inputRect.centerX() + cursorWidth / 2f), (int) ((inputRect.height() - cursorHeight) / 2f + cursorHeight));

                textCursorDrawable.draw(canvas);

                isShowCursor = true; //控制光标闪烁 blinking

            } else {

                isShowCursor = false;//控制光标闪烁 no blink

            }

            removeCallbacks(invalidateCursor);

            postDelayed(invalidateCursor,500);

        }

    }

}


paint.setColor(color);

paint.setStyle(style);

paint.setTextAlign(align);


canvas.restoreToCount(saveCount);

总结

上面就是本文的核心逻辑，实际上EditText、Button都继承自TextView，因此我们简单的修改就能让其支持输入，主要原因还是TextView复杂的设计和各种Layout的支持，但是这也给TextView带来了性能问题。

这里简单说下TextView性能优化，对于单行文本和非可编辑文本，最好是自行实现，单行文本直接用canvas.drawText绘制，当然多行也是可以的，不过鉴于要支持很多特性，多行文本可以使用StaticLayout去实现，但单行文本尽量自己绘制，也不要使用BoringLayout，因为其存在一些兼容性问题，另外自定义的单行文本不要和TextView同一行布局，因为TextView的计算相对较多，很可能产生对不齐的问题。

本篇全部代码

按照惯例，这里依然提供全部代码，仅供参考。

public class EditableTextView extends TextView {

private RectF inputRect = new RectF();


//边框颜色
private int boxColor = Color.BLACK;

//光标是否可见
private boolean isCursorVisible = true;
//光标
private Drawable textCursorDrawable;
//光标宽度
private float cursorWidth = dp2px(2);
//光标高度
private float cursorHeight = dp2px(36);
//光标闪烁控制
private boolean isShowCursor;
//字符数量控制
private int inputBoxNum = 5;
//间距
private int mBoxSpace = 10;
// box radius
private float boxRadius = dp2px(0);


    InputFilter[] inputFilters = new InputFilter[]{
new InputFilter.LengthFilter(inputBoxNum)

    };


public EditableTextView(Context context) {
this(context, null);

    }

public EditableTextView(Context context, AttributeSet attrs) {
this(context, attrs, 0);

    }

public EditableTextView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
super.setFocusable(true); //支持聚焦
super.setFocusableInTouchMode(true); //支持触屏模式聚焦
//可点击，因为在触屏模式可聚焦的view一般是可以点击的，这里你也可以设置个clickListener，效果一样
super.setClickable(true);
super.setGravity(Gravity.CENTER_VERTICAL);
super.setMaxLines(1);
super.setSingleLine();
super.setFilters(inputFilters);
super.setLongClickable(false);// 禁止复制、剪切
super.setTextIsSelectable(false); // 禁止选中

Drawable cursorDrawable = getTextCursorDrawable();
if(cursorDrawable == null){

            cursorDrawable = new PaintDrawable(Color.MAGENTA);

            setTextCursorDrawable(cursorDrawable);

        }

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
super.setPointerIcon(null);

        }
super.setOnLongClickListener(new OnLongClickListener() {
@Override
public boolean onLongClick(View v) {
return true;

            }

        });

//禁用ActonMode弹窗
super.setCustomSelectionActionModeCallback(new ActionMode.Callback() {
@Override
public boolean onCreateActionMode(ActionMode mode, Menu menu) {
return false;

            }

@Override
public boolean onPrepareActionMode(ActionMode mode, Menu menu) {
return false;

            }

@Override
public boolean onActionItemClicked(ActionMode mode, MenuItem item) {
return false;

            }

@Override
public void onDestroyActionMode(ActionMode mode) {


            }

        });

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {

            setBreakStrategy(LineBreaker.BREAK_STRATEGY_SIMPLE);

        }

        mBoxSpace = (int) dp2px(10f);


    }

@Override
public ActionMode startActionMode(ActionMode.Callback callback) {
return null;

    }

@Override
public ActionMode startActionMode(ActionMode.Callback callback, int type) {
return null;

    }

@Override
public boolean hasSelection() {
return false;

    }

@Override
public boolean showContextMenu() {
return false;

    }

@Override
public boolean showContextMenu(float x, float y) {
return false;

    }

public void setBoxSpace(int mBoxSpace) {
this.mBoxSpace = mBoxSpace;

        postInvalidate();

    }

public void setInputBoxNum(int inputBoxNum) {
if (inputBoxNum <= 0) return;
this.inputBoxNum = inputBoxNum;
this.inputFilters[0] = new InputFilter.LengthFilter(inputBoxNum);
super.setFilters(inputFilters);

    }

@Override
public void setClickable(boolean clickable) {


    }

@Override
public void setLines(int lines) {


    }
@Override
protected boolean getDefaultEditable() {
return true;

    }


@Override
protected void onDraw(Canvas canvas) {

TextPaint paint = getPaint();

float strokeWidth = paint.getStrokeWidth();
if(strokeWidth == 0){
//默认Text是没有strokeWidth的，为了防止绘制边缘存在问题，这里强制设置 1dp

            paint.setStrokeWidth(dp2px(1));

            strokeWidth = paint.getStrokeWidth();

        }

        paint.setTextSize(getTextSize());

float boxWidth = (getWidth() - strokeWidth * 2f - (inputBoxNum - 1) * mBoxSpace) / inputBoxNum;
float boxHeight = getHeight() - strokeWidth * 2f;
int saveCount = canvas.save();


        Paint.Style style = paint.getStyle();

        Paint.Align align = paint.getTextAlign();

        paint.setTextAlign(Paint.Align.CENTER);

String text = getText().toString();
int length = text.length();

int color = paint.getColor();

for (int i = 0; i < inputBoxNum; i++) {


            inputRect.set(i * (boxWidth + mBoxSpace) + strokeWidth,

                    strokeWidth,

                    strokeWidth + i * (boxWidth + mBoxSpace) + boxWidth,

                    strokeWidth + boxHeight);


            paint.setStyle(Paint.Style.STROKE);

            paint.setColor(boxColor);
//绘制边框

            canvas.drawRoundRect(inputRect, boxRadius, boxRadius, paint);

//设置当前TextColor
int currentTextColor = getCurrentTextColor();

            paint.setColor(currentTextColor);

            paint.setStyle(Paint.Style.FILL);
if (text.length() > i) {
// 绘制文字，这里我们不过滤空格，当然你可以在InputFilter中处理
String CH = String.valueOf(text.charAt(i));
int baseLineY = (int) (inputRect.centerY() + getTextPaintBaseline(paint));//基线中间点的y轴计算公式

                canvas.drawText(CH, inputRect.centerX(), baseLineY, paint);

            }

//绘制光标
if(i == length && isCursorVisible && length < inputBoxNum){
Drawable textCursorDrawable = getTextCursorDrawable();
if(textCursorDrawable != null) {
if (!isShowCursor) {

                        textCursorDrawable.setBounds((int) (inputRect.centerX() - cursorWidth / 2f), (int) ((inputRect.height() - cursorHeight) / 2f), (int) (inputRect.centerX() + cursorWidth / 2f), (int) ((inputRect.height() - cursorHeight) / 2f + cursorHeight));

                        textCursorDrawable.draw(canvas);

                        isShowCursor = true; //控制光标闪烁 blinking

                    } else {

                        isShowCursor = false;//控制光标闪烁 no blink

                    }

                    removeCallbacks(invalidateCursor);

                    postDelayed(invalidateCursor,500);

                }

            }

        }


        paint.setColor(color);

        paint.setStyle(style);

        paint.setTextAlign(align);


        canvas.restoreToCount(saveCount);

    }


private Runnable invalidateCursor = new Runnable() {
@Override
public void run() {

            invalidate();

        }

    };
/**

     * 基线到中线的距离=(Descent+Ascent)/2-Descent

     * 注意，实际获取到的Ascent是负数。公式推导过程如下：

     * 中线到BOTTOM的距离是(Descent+Ascent)/2，这个距离又等于Descent+中线到基线的距离，即(Descent+Ascent)/2=基线到中线的距离+Descent。

     */
public static float getTextPaintBaseline(Paint p) {

        Paint.FontMetrics fontMetrics = p.getFontMetrics();
return (fontMetrics.descent - fontMetrics.ascent) / 2 - fontMetrics.descent;

    }

/**

     * 控制是否保存完整文本

     *

     * @return

     */
@Override
public boolean getFreezesText() {
return true;

    }

@Override
public Editable getText() {
return (Editable) super.getText();

    }

@Override
public void setText(CharSequence text, BufferType type) {
super.setText(text, BufferType.EDITABLE);

    }

/**

     * 控制光标展示

     *

     * @return

     */
@Override
protected MovementMethod getDefaultMovementMethod() {
return ArrowKeyMovementMethod.getInstance();

    }

@Override
public boolean isCursorVisible() {
return isCursorVisible;

    }

@Override
public void setTextCursorDrawable(@Nullable Drawable textCursorDrawable) {
//        super.setTextCursorDrawable(null);
this.textCursorDrawable = textCursorDrawable;

        postInvalidate();

    }

@Nullable
@Override
public Drawable getTextCursorDrawable() {
return textCursorDrawable;  //支持android Q 之前的版本

    }

@Override
public void setCursorVisible(boolean cursorVisible) {

        isCursorVisible = cursorVisible;

    }
public float dp2px(float dp) {
return TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dp, getResources().getDisplayMetrics());

    }

public void setBoxRadius(float boxRadius) {
this.boxRadius = boxRadius;

        postInvalidate();

    }

public void setBoxColor(int boxColor) {
this.boxColor = boxColor;

        postInvalidate();

    }

public void setCursorHeight(float cursorHeight) {
this.cursorHeight = cursorHeight;

        postInvalidate();

    }

public void setCursorWidth(float cursorWidth) {
this.cursorWidth = cursorWidth;

        postInvalidate();

    }


}